The present invention is directed toward inflation systems, in particular toward inflation systems used for inflating an inflatable member such as an emergency evacuation slide used on a commercial aircraft.
Inflatable evacuation slides are normally stored folded in an uninflated condition in a pack requiring a minimum amount of space. Typically the pack is stored in a compartment attached to or immediately adjacent the aircraft exit door. The slide is typically attached to the airframe such that if the aircraft exit door is opened in the xe2x80x9carmedxe2x80x9d condition, the evacuation slide will be automatically ejected and inflated. For over-wing evacuation systems, the evacuation slide is most commonly stored outside the aircraft pressure hull in an enclosure within the contour of the aircraft skin on the fuselage, wing or fairing. The enclosure has a door that fits flush with the external skin of the aircraft. The door is remotely actuated to fall away as the evacuation slide is inflated. For aerodynamic reasons it is desirable that the remotely actuated door fit tight and flush against the external skin of the aircraft. Similarly, in order to prevent water, de-icing fluids or other containments from entering the evacuation slide enclosure, it is desirable that a seal be maintained between the door and the evacuation slide enclosure.
Modern evacuation slide inflation systems typically comprise a pressure vessel containing a stored pressurized gas, either alone or in combination with a pyrotechnic gas generator, used to supply the source gas for inflation of the emergency evacuation slide. Regulations require inflation systems that use stored gas to have an overpressure relief valve to release gas in the event of overpressurization of the inflation system pressure vessel. Typically such overpressure relief valves vent excess gas through a diffuser that vents the excess gas to the atmosphere. Because of the relatively large volume inside an aircraft cabin, for cabin-mounted inflation systems, venting of an overpressure relief valve to the atmosphere does not pose any serious safety concerns. For externally mounted inflation systems, however, pressure build-up within the evacuation system enclosure resulting from the venting of an overpressure relief valve could result in a catastrophic in-flight separation of the enclosure door or enclosure itself from the aircraft. Thus, what is needed is a an inflation system having a tight, flush fitting enclosure door while at the same time having a control valve that safely vents gas from an overpressure relief valve without overpressurizing the emergency evacuation slide enclosure.
The present invention solves the foregoing need by providing an inflation system for inflating an inflatable evacuation slide that includes an overboard venting means for safely venting gas from an overpressure relief valve or other safety device without overpressurizing the enclosure or its surroundings. According to one embodiment of the invention, the inflation system comprises an enclosure containing an uninflated evacuation slide. The enclosure is sealed by means of a tightly fitting enclosure door that optionally includes a seal for excluding dirt and moisture. The system also includes a source of pressurized gas comprising a conventional pyrotechnic gas generator, stored pressurized gas, or hybrid inflator consisting of at least of at least one stored inflation gas augmented by a pyrotechnic gas generator. The inflation system includes a control valve that, in response to a trigger such as from opening an emergency evacuation door in the xe2x80x9carmedxe2x80x9d condition, opens to begin a flow of inflation gas from the pressure vessel to the emergency evacuation slide. The control valve may optionally include a regulator that regulates the relatively high pressure in the storage vessel down to a lower pressure for safe inflation of the emergency evacuation slide or, if aspirators are used, down to the optimum pressure for operation of the aspirators. The control valve includes an overpressure relief vent, which vents inflation gas outside of the inflatable member. In lieu of the neutral thrust overpressure relief vents used in prior art regulator valves, however, the overpressure relief vent of the present invention comprises a directional vent connected to a conduit. The conduit passes from the control valve to an opening in the aircraft fuselage, which allows any vented gas to be safely directed away from the inflation system enclosure.